2n2222

[watzmann]

please check this schematic may be i have something wrong , i'm going to make it's PCB,

the function of this board is to get a signal from PIC16f877 main board and run H-Bridges and other circuits which required 5V or 12 Volt but with more tolerance with the current

i'm using 2n2222


thank you

 

[blueroomelectronics]

Looks fine, most use a ULN2803 to do the same thing as it has the diode clamps and higher gain than the 2N2222A plus a nice simple DIP package.
**broken link removed**

 

[audioguru]

Your circuit doesn't have resistor values nor does it have a load. So it might work, it might not work or it might blow up.

If it is designed properly:
When an input is high then the output of a transistor is low.
When an input is low then the output of a transistor is high.

 

[watzmann]

actually i don't know how yo use this ULN2803 , but i'll download it's datasheet and i'll try to understand it .

if you can help please tell me , what is this circus , it looks like stepper motor

 

[watzmann]

looked at the datasheet , my question is :

the output is just 500mA and 50 Volts

how to increase this 500 mA , it's so low

 

[Nigel Goodwin]

It was a stepper motor, a common use for that IC.

 

[blueroomelectronics]

looked at the datasheet , my question is :

the output is just 500mA and 50 Volts

how to increase this 500 mA , it's so low

In that case the 2N2222 isn't that much more powerful at 800ma and you'll need to drive it fairly hard to get that and it will get very warm. A TIP112 darlington might be a better idea.
500ma is generally enough for many small stepper motors.

 

[Hero999]

How large is your stepper motor?

Perhaps power MOSFETs might be a better option.

 

[watzmann]

i don't need to drive stepper motors , but i just have four H-Bridge circuits which drives 4 DC motors , i think each one about 1A,

for that raeson i'm asking for more current.

as for the TIP 112 should i use a buffer before connecting it with the pic

 

[ericgibbs]

i don't need to drive stepper motors , but i just have four H-Bridge circuits which drives 4 DC motors , i think each one about 1A,

for that raeson i'm asking for more current.

as for the TIP 112 should i use a buffer before connecting it with the pic

hi,
The TIP122 is a medium power npn darlington, with a gain of about 1000.

For TIP122 collector currents of about 2amps or so, all you need is a PIC pin to TIP 122 base resistor, say about 270R.

 

[blueroomelectronics]

i don't need to drive stepper motors , but i just have four H-Bridge circuits which drives 4 DC motors , i think each one about 1A,

for that raeson i'm asking for more current.

as for the TIP 112 should i use a buffer before connecting it with the pic

Better to use a SN754410 Quad Half Bridge. 1.2A with thermal shutdown, nice part. Of course larger ICs exist and will save you burning out transistors. Your original 2N2222 circuit is not an H-Bridge, you'll need PNP transistors too for a proper H-Bridge.

 

[audioguru]

Unlike good Mosfets, darlington transistors have a voltage loss. An H-bridge made with darlingtons could have a loss of up to 6V.

A "1A" motor draws 10A or more when it starts and when it is stalled.

Try this H-bridge that uses darlingtons:

 

[watzmann]

Your original 2N2222 circuit is not an H-Bridge, you'll need PNP transistors too for a proper H-Bridge.

Yes my original circuit 2n2222 is not an H-bridge , it's just a connection between the PIC main control circuit and the H-bridge ,

my H-bridge is working very well and up to 1.5A,

but i'll try the new one as it's for 5A , may be i need that capacity later

 

[Hero999]

I would recommend the IRL540 MOSFET.

 

[audioguru]

This circuit uses N-channel and P-channel Mosfets.